Childhood asthma is a significant public health problem accounting for the majority of school absences and significant direct and indirect health costs. There is a clear association between exposure to air pollution and cardiac and respiratory health. Increases in airborne particulate matter (tiny particles of solid or liquid suspended in a gas) levels are associated with asthma exacerbations. It is unknown, however, whether childhood asthma prevalence is attributable to air pollution. We hypothesize that particulate matter exposure accounts for differences in childhood asthma prevalence in Chicago neighborhoods. A cross- sectional survey administered by the Chicago Initiative to Raise Asthma Health Equity (CHIRAH) among school-aged children determined neighborhood asthma prevalence rates. Our preliminary data indicate that race and socioeconomic status do not fully explain differences between neighborhood childhood asthma prevalence rates. The Multi-Ethnic Study of Atherosclerosis (MESA) Air Ancillary Study examines individual-level assessment of long-term ambient air pollution exposures to progression of subclinical cardiovascular disease in Chicago and other US cities. MESA Air has greater than 50 monitors overlapping with the CHIRAH geographic region of interest and multiple sources of traffic data. Linkage of data from these studies allow for estimation of particulate matter and traffic exposure at the homes and schools of nearly 50,000 children. We aim to determine if particulate matter levels at individual children's home and schools in Chicago are associated with asthma prevalence. We will examine if traffic-related exposures as indicated by children's residential and school proximity to major roadways are associated with asthma prevalence. We will estimate particulate matter concentrations and traffic exposure controlling for personal and neighborhood confounders (age, BMI, sex, race/ethnicity, education, household members with asthma, and neighborhood income). This line of investigation will enhance my career development by allowing me to gain experience using primary epidemiologic data and expand my understanding of how air pollution affects respiratory health. PUBLIC HEALTH RELEVANCE: The rise in asthma prevalence and its economic burden present a significant public health concern. A better understanding of the relationship between exposure to particulate matter and childhood asthma will directly inform preventive measures that may impact this disease.